Don't get too worried about it. While it's true that this may not be a Sigil-specific question, you did mention that you were using a Sigil feature that prompted you to go searching. So no real harm or foul. The proper response would probably include some helpful advice as to what
would be the proper place to ask such questions. To which I would suggest the ePub format forum. I may move your question there, but please don't feel that it's a failure on your part (or punishment on mine) if I do so. "Help first" is my motto.